Support managed_disk_type

Add support for specifying managed_disk_type.  This is a prerequisite
for supporting snapshots.

fixes #99

roles/azure_virtual_machine_with_public_ip/meta/argument_specs.yml

@@ -70,6 +70,20 @@ argument_specs:
               - The image used to build the VM. For custom images, the name of the image. To narrow the search to a specific resource group, a dict with the keys name and resource_group.
               - For Marketplace images, a dict with the keys publisher, offer, sku, and version.
               - Set O(version=latest) to get the most recent version of a given image.
+          managed_disk_type:
+            type: "str"
+            description:
+              - Managed OS disk type.
+              - Create OS disk with managed disk if defined.
+              - If not defined, the OS disk will be created with virtual hard disk (VHD).
+            choices:
+              - "Standard_LRS"
+              - "StandardSSD_LRS"
+              - "StandardSSD_ZRS"
+              - "Premium_LRS"
+              - "Premium_ZRS"
+              - "UltraSSD_LRS"
+            required: false
           ssh_pw_enabled:
             description: Enable/disable SSH passwords.
             choices: ['yes', 'no']

roles/azure_virtual_machine_with_public_ip/tasks/create.yml

@@ -131,6 +131,7 @@
     vm_size: "{{ azure_virtual_machine_with_public_ip_vm.size | default(omit) }}"
     network_interfaces: "{{ azure_virtual_machine_with_public_ip_vm.network_interfaces | default(vm_name) }}"
     os_type: "{{ azure_virtual_machine_with_public_ip_vm.os | default(omit) }}"
+    managed_disk_type: "{{ azure_virtual_machine_with_public_ip_vm.managed_disk_type | default(omit) }}"
     availability_set: "{{ azure_virtual_machine_with_public_ip_availability_set.name | default(omit) }}"
     image: "{{ azure_virtual_machine_with_public_ip_vm.image | default(omit) }}"
     admin_username: "{{ azure_virtual_machine_with_public_ip_vm.admin_username | default(omit) }}"